【作者】 黄微雅；

【导师】 张渊明；

【作者基本信息】 暨南大学 ， 水生生物学， 2013， 博士

【摘要】 磷是水体生物所必须的营养物质之一，然而当水中磷含量过多时会导致水体富营养化，从而严重危害水体生态系统。废水除磷是延缓水体富营养化的有效手段，也是目前环境领域的研究热点。除磷的方法有多种，其中吸附法具有操作简单、方便、不产生有毒物质等无可比拟的优势。目前所研究报道的除磷吸附剂有很多种，然而普遍存在吸附容量低、吸附速率慢或价格昂贵等不足，因此设计和开发新型高效的吸附剂仍然是研究者不断努力的方向。本论文开展了以下四方面的研究：1)功能化介孔吸附剂的制备和除磷性能研究；2)功能化大孔-介孔吸附剂的制备和除磷性能研究；3)功能化多孔层次结构吸附剂的制备和除磷性能研究；4)功能化改性粘土吸附剂的制备和除磷性能研究。对于功能化介孔吸附剂的制备和除磷性能研究，本文采用一步法合成了乙二胺功能化的介孔MCM-41和SBA-15两种吸附剂。其中在功能化SBA-15的合成上，首次采用NH4F辅助缩聚法合成了不同乙二胺负载量的功能化介孔SBA-15吸附剂。研究发现，随着合成过程中乙二胺官能团含量的增加，吸附剂的吸附量增大，其中当乙二胺官能团和二氧化硅摩尔比在0.5:1时，所合成的吸附剂吸附容量最大，高达20.7mg P/g。吸附数据的拟合显示，Langmuir方程比Freundlich方程拟合后的相关性系数更高，说明吸附过程为单分子层吸附；并且二级动力学方程的相关性系数为0.999，远高于一级动力学，说明吸附过程为化学吸附。此外，溶液的初始pH对吸附效果的影响较大，在pH为3.0-6.0之间时，吸附效果较好；共存离子Cl^-和NO₃^-对吸附剂的吸附性能影响较小，而HCO₃^-和SO₄^2-的影响较大。在脱附实验中，90%以上所吸附的磷离子可以在0.010M NaOH溶液中脱附，说明该吸附剂具有可再生性能。对于功能化大孔-介孔层次结构吸附剂的制备和除磷性能研究方面，本文采用双模板（P123和PS球）法合成了大孔-介孔层次结构SBA-15，并采用后嫁接法在其表面接枝了乙二胺官能团，然后与Fe（III）和Al（III）配位制备了Fe（III）-乙二胺功能化介孔吸附剂和Al（III）-乙二胺功能化介孔吸附剂。静态除磷吸附实验发现，Fe（III）-乙二胺功能化介孔吸附剂的Langmuir最大吸附量为12.7mg P/g，吸附进行1min后，初始溶液中92.5%的磷酸根可以被吸附去除。Al（III）-乙二胺功能化介孔吸附剂的最大吸附量可达23.59mg P/g，吸附进行1min后，初始溶液中95%的磷可被去除，而相同条件下所合成的介孔吸附剂，其1min的去除率则只有79%。此外，当溶液的pH值在3.0-6.0之间有利于吸附；干扰离子如F-等对吸附剂的吸附性能影响较大。在功能化多孔层次结构吸附剂的制备和除磷性能研究上，本文首次合成了La₂O₃负载的介孔空心微球吸附剂用于除磷研究。通过乙醇蒸发法在所合成的二氧化硅介孔空心微球表面负载了一系列不同含量的La₂O₃。采用静态吸附法系统地研究了所合成吸附剂的除磷性能，研究发现La₂O₃负载可有效提高吸附剂的吸附容量（无负载的空心介孔微球吸附剂基本上不能吸附除磷）。其中，当La的加入量和Si的摩尔比为1:5时，所合成的功能化空心微球介孔吸附剂的吸附容量最大，拟合后的Langmuir最大吸附量为47.89mg P/g。动力学研究发现，吸附过程符合二级动力学模型，说明该吸附为化学吸附。溶液pH值范围在3.0-8.0之间时，该吸附剂的吸附效果较好；并且0.01M的其他共存离子(如：F^-, Cl^-, NO₃^-, SO₄^2-和CO₃^2-)对吸附效果几乎没有影响。采用一步法首次合成了具有不规则层次介孔的La（OH）₃吸附剂，并研究了其除磷性能。各项分析结果显示，所合成吸附剂的形貌近似球形，直径大小约为200nm，内部存在很多大小和形状不规则的层次介孔，其平均介孔孔径为8.74nm。吸附剂的吸附过程为化学吸附，并且Langmuir最大吸附量为57.65mg P/g。在功能化改性粘土吸附剂的制备和除磷性能研究方面，本文成功合成了两种不同金属氢氧化物功能化改性的粘土吸附剂，并且系统地研究了这两种吸附剂的吸附性能。ⅰ)首次合成了一系列La（OH）₃改性的膨胀蛭石（EV），并研究了初始溶度、吸附时间、温度、pH值和共存离子等各项因素对吸附的影响。当La/EV为5.00mmol/g时，所合成的吸附剂具有较高的吸附容量，其Langmuir最大吸附量高达79.6mg P/g，而未改性EV的吸附量只有约2mg P/g。当pH为3.0-7.0时，吸附剂的吸附量较大；共存离子F^-, Cl^-, NO₃^-,和SO₄^2-对吸附量几乎没有影响。吸附-再生循环研究发现，该吸附剂具有一定的再生循环利用的价值。ⅱ)合成了一系列β-FeOOH改性的红土吸附剂，并研究了其吸附性能。所合成吸附剂的去除率可高达90.12%，比未改性的吸附剂高37.47%。结合XRD、BET、SEM等各项表征证实，改性后吸附剂的比表面和孔容增大，并且在红土表面生成β-FeOOH颗粒，这是吸附量增大的主要原因。系统研究了吸附时间、初始磷溶液的浓度、温度、pH值和共存离子等对吸附性能的影响，并对其吸附机理进行了探讨。该吸附剂在经历四次吸附-再生循环后，吸附量没有明显的降低，说明该吸附剂具有潜在的实际应用价值。更多还原

【Abstract】 Phosphorus is the key nutrients in the growth of organisms in ecosystems. However, the excessivepresence of phosphorous in aquatic environment contributes to eutrophication, in which one of examples isalgal bloom, a serious world-wide environmental problem. Various methods have been widely studied toremoval phosphate from aqueous solution, among which the adsorption-based process is considered as one ofthe most efficient routes to remove phosphate, due to its simplicity, high level of efficiency and fast removalrate, especially at low phosphate concentrations. However, many adsorbents reported are far more thansatisfied, adsorbents with a high adsorption capacity and fast adsorption rate for phosphate are highly neededin the fields of water treatment and purification. Considering the above demands, the thesis is conducted basedon the following three areas:1) preparation of functionalized mesoporous adsorbents and study of theiradsorption capacities;2) preparation of functionalized macroporous-mesoporous adsorbents and study of theiradsorption capacities;3) fabrication of hierarchical adsorbents and investigation of their adsorption capacities;4) synthesis of modified clays and study of their adsorption capacities.Firstly, two functionalized mesoporous adsorbents, i.e. Fe（Ш）-coordinated mesoporous silica adsorbentsMCM-41and SBA-15were successfully synthesized and used for phosphate removal study. TheFe（Ш）-coordinated mesoporous SBA-15adsorbents were prepared by a new NH4F-assisted co-condensationmethod and impregnation of Fe³⁺cations. In the batch adsorption tests, the functionalized absorbents withincreasing loadings of diamino groups possessed markedly enhanced adsorption capacities, although there wasa gradual loss of ordered mesostructures accompanied. In particular, for the resulting absorbent prepared with0.5:1molar ratio of AAPTS and TEOS, the maximum phosphate capture capacity calculated from Langmuirmodel is20.7mg P/g. The phosphate adsorption efficiency of prepared absorbent was highly pH-dependentand the high removal of phosphate was achieved within the pH between3.0and6.0. The presence of Cl^-andNO₃^-exhibited small impacts on the phosphate adsorption by using our synthesized absorbent; whereas, therewere significantly negative effects from HCO₃^-and SO₄^2- on the phosphate removal. In0.010M NaOH, morethan90%of the absorbed phosphate anions on the spent adsorbent could be desorbed, suggesting the absorbentwith a capacity of regeneration.Secondly, two macroporous–mesoporous SBA-15phosphate adsorbent was synthesized via adual-templating approach, followed by diamino-functionalization, Fe（III） and Al（III） impregnation, i.e.Fe（III）-coordinated diamino-functionalized macroporous-mesoporous adsorbent and Al（III）-coordinated diamino-functionalized macroporous-mesoporous adsorbent. The resulting Fe（III）-coordinateddiamino-functionalized macroporous-mesoporous adsorbent possessed a maximum adsorption capacity of12.7mg P/g, and92.5%of the final adsorption capacity reached in the first1min. While Al（III）-coordinateddiamino-functionalized macroporous-mesoporous adsorbent had a maximum adsorption capacity of23.59mgP/g. In the kinetic study, over95%of its final adsorption capacity reached in the first1min. Besides, pHranging from3.0to6.0favored the high phosphate adsorption of hierarchically porous adsorbent; however, thecoexistence of other anions, especially F^-, retarded the adsorption.Thirdly, hollow silica microspheres with ordered mesoporous shell （HMS） were impregnated withdifferent loadings of Lanthanum as novel adsorbents for phosphate removal. In batch adsorption tests, theHMS-x adsorbents possessed markedly enhanced adsorption capacities with increasing La amounts, ascompared to HMS which can hardly adsorbed any phosphate in solution. In particular, HMS-1/5possesses amaximum phosphate capture capacity of47.89mg P/g. In the kinetic study, the phosphate adsorption followedpseudo-second-order equation well. High adsorption capacities were achieved by HMS-1/5within the pHbetween3.0and8.0, and high selectivity to phosphate was also observed with the coexisting of0.01M otheranions (e.g. F^-, Cl^-, NO₃^-, SO₄^2- and CO₃^2-). Besides, Hierachical mesoporous La（OH）₃adsorbent wassynthesized by one-pot method and its application in phosphate removal was reported for the first time. Thesynthesized P-La（OH）₃sample exhibited a particle diameter of approximately200nm and possessed irregularmesopores with a pore diameter of8.74nm. In the phosphate adsorption test, the adsorbent had a maximumphosphate adsorption capacity of57.65mg P/g, showing a great potential for use in the practical removal ofphosphate.Finally, two kinds of clays modified by metal hydroxides were successfully synthesized and theirphosphate removal performance are summariezed as following:ⅰ) La（OH）₃-modified exfoliated vermiculites were fabricated, characterized, and investigated for phosphateremoval in batch tests for the first time. The BET surface area of the adsorbent, which was synthesized in thesolution consisting of5.00mmol/g La/exfoliated vermiculite （EV）, was significantly increased, accompaniedwith a larger pore diameter and greater total pore volume, as compared with the unmodified EV. Effects ofinitial phosphate concentration, contact time, temperature, pH, and co-existing ions on the adsorption capacitywere investigated in detail. The experimental equilibrium data were fitted better by using the Langmuir model（maximum adsorption capacity of79.6mg P/g）. The adsorbent exhibited a high adsorption capacity in the pHrange of3.0-7.0. The addition of F, Cl, NO3, and SO42-had neglectable effects on its phosphate removal capacities. The spent adsorbent could be regenerated and reused in phosphate adsorption; that could removemore than70%phosphate in the3rd adsorption-desorption cycle.ⅱ) The phosphate removal performances of a series of ferric-modified laterites （ML） were tested andcompared with raw laterite （RL） in this study. After the modification with0.5MFeCl₃solution, the resultingadsorbent ML-C exhibited90.12%of phosphate removal, which was37.47%higher than that of RL underthe same experimental condition. This may be attributed to the significant increase of BET surface area andtotal pore volume for ML-C, arising from the formation of akaganeite. The effects of contact time, initialphosphate concentration, temperature, pH, and co-existing ions on the adsorption capacity of ML-C wereinvestigated in detail. In the reusability study, the adsorbent showed no significant loss in their adsorptionperformance after four adsorption-desorption cycles, indicating that ML-C was able to be utilized as a potentialcost-effective phosphate adsorbent for practical applications.更多还原